1. Technical Field
The present invention relates to an electric disk brake having an electric motor to press a brake pad against a disk rotor to exert a braking force; a caliper for the electric disk brake; a motor/controller unit adapted for use in the electric disk brake; and a method for assembling the caliper for the electric disk brake.
2. Related Art
Examples of electric disc brakes are disclosed in Japanese Patent Public Disclosure No. 2000-304076, and in Japanese Patent Public Disclosure No. 2003-137081. In these references, electric disc brakes are described which use a rotary-to-linear motion conversion mechanism such as a ball screw mechanism or a ball ramp mechanism to convert a rotary motion of a rotor of an electric motor to a linear motion of a piston, which is adapted to press a brake pad against a disk rotor to exert a braking force. Further, these electric disk brakes use a sensor to detect a force (or an amount of displacement) which a driver applies to a brake pedal. Based on a detected value, rotation of the electric motor is controlled to exert a desired braking force.
In the electric disk brake disclosed in Japanese Patent Public Disclosure No. 2000-304076, a claw portion of a brake caliper is provided with a ball ramp mechanism, a speed reduction mechanism, and so on, each of which are sub-assembled to form an opening/closing mechanism. Further, an electric motor, a rotational-position sensor, and so on are sub-assembled in a case and a cover to form a motor mechanism. Subsequently, the opening/closing mechanism and the motor mechanism are joined together in an assembling process. The assembling process, which involves sub-assembly steps for the mechanisms mentioned, is aimed at improving assembly efficiency.
The electric disk brake disclosed in Japanese Patent Public Disclosure No. 2003-137081 is provided with a drive controller for controlling operation of an electric motor, the drive controller being integrated into a brake caliper to simplify wiring of a power line and a control-signal line connecting a vehicle-mounted controller, which is mounted on a vehicle body, and a brake caliper so as to reduce an adverse effect of noise and a power loss.
However, in Japanese Patent Public Disclosure No. 2000-304076, the electric motor and its drive controller are placed apart from each other and are connected via a cable. This structure is prone to problems such as the adverse effect of noise and power loss.
On the other hand, in Japanese Patent Public Disclosure No. 2003-137081, constituent components including the piston, the rotary-to-linear motion conversion mechanism, the electric motor, and the drive controller are required to be individually incorporated into the brake caliper. This makes assembling and disassembling operations complicated. Further, an operation check can be conducted only after all of the constituent components have been assembled. This makes it difficult to detect any defect in each component during a manufacturing or repairing process.